The spread of computer networks linking workplaces, homes, communities, and social services will alter the way people communicate. This proposal describes social psychological research on computer-mediated communication specifically, and more generally, on the implications of computer networks for social networks and mental health. A preliminary social psychological model posits that computer networks, by virtue of their technical and cultural features, may change social contact patterns, including, for example, anlarging the number of work and social groups to which people belong, increasing the number of avenues to social support, and in work organizations, increasing communication across organizational boundaries and the communication of nonsocial data. These changes could have secondary permanent effects on psychological states and interpersonal relationships in groups and organizations, such as increased potential for computer-mediated acquantanceships to provide social support and more organizational participation. Understanding how computer networks become social networks, along with knowledge of their benefits and risks, might lead to useful applications of computer networks in metal health prevention programs, long-distance service delivery, and information systems.